Field of the Invention
The present disclosure relates to adjusting control of the density of an image formed by an image forming apparatus.
Description of the Related Art
Electrophotographic image forming apparatuses include a charging unit that electrically charges a photosensitive member, an exposing unit that exposes the photosensitive member with a laser beam to form an electrostatic latent image on the photosensitive member, and a developing unit that develops the electrostatic latent image. The developing unit develops the electrostatic latent image with a developer to visualize the image. The image forming apparatus further includes a transfer unit and a fixing unit. The transfer unit transfers the image on the photosensitive member onto a sheet. The fixing unit fixes the image on the sheet to the sheet. Thus, an image is formed on the sheet.
To adjust the density of the image to desired density, an image forming apparatus disclosed in U.S. Pat. No. 5,566,372 forms a measurement image on an image bearing member and corrects a conversion condition for converting image data on the basis of the result of measurement of the measurement image using a measuring means. The image forming apparatus disclosed in U.S. Pat. No. 5,566,372 forms the measurement image on the image bearing member when a power switch is turned on and corrects the conversion condition on the basis of the result of measurement with the measuring means.
However, a plurality of images formed by the image forming apparatus can change in density while being continuously formed. For this reason, to reduce changes in image density while continuously forming a plurality of images, image forming apparatuses need to form a measurement image on the image bearing member at predetermined timing and to correct the conversion condition on the basis of the result of measurement of the measurement image with the measuring means.
Some image forming apparatuses form a color image after forming a monochrome image. In such a case, when the density of an image of a color different from black changes while the image forming apparatuses are continuously forming a plurality of monochrome images, the density of a color image formed after the monochrome images cannot have desired density.